| 摘要 |
1515937 Speech scrambling TEKADE FELTEN & GUILLEAUME FERNMELDEANLAGEN GmbH 24 Nov 1975 [23 Nov 1974] 48228/75 Heading H4R Speech is scrambled by interchanging equal duration sections according to a pseudo random number sequence which is modified wherever the encoded speech would resemble clear speech. The speech sections are read-in to registers 0-7 or a direct link D according to the number sequence whilst the numbers of the one preceding and two succeeding registers, in this case 1 and 3, 4 are stored in register K, representing prohibited sections. Each new register address is compared in V with those in K and if match exists unity is added to the addressed number and comparison repeated until no match occurs, whereupon that number opens switches W1, W2 to the corresponding register. Detector BC inserts the direct link D to prevent loss, and repetition may be effected if the level of a section is too low. Reference has been directed by the Comptroller to Specification 1,353,693. |
